fix build on MRI1.9, 2.0.0
fix build on MRI1.9, 2.0.0

sideci-sample/sideci-sample-pry,gfvcastro/pry,tdg5/pry,scalixte-mdsol/pry,josue804/debunker,shockone/pry,tdg5/pry,ooohiroyukiooo/pry,icebreaker/pry,nju520/pry,raeno/pry,caporta/pry,scalixte-mdsol/pry,icebreaker/pry,raeno/pry,pvdb/pry,jasonm23/pry,jasnow/pry,shockone/pry,geoffreylitt/pry,raeno/pry,85x14/pry,jasonm23/pry,sferik/pry,nju520/pry,85x14/pry,shockone/pry,scalixte-mdsol/pry,ngpestelos/pry,printercu/pry,ooohiroyukiooo/pry,geoffreylitt/pry,85x14/pry,tdg5/pry,bronzdoc/pry,gfvcastro/pry,printercu/pry,nju520/pry,ngpestelos/pry,bronzdoc/pry,sferik/pry,jasonm23/pry,caporta/pry,jasnow/pry,jasnow/pry,ooohiroyukiooo/pry,caporta/pry,josue804/debunker,pvdb/pry